To factor x3 + ax - 3a - 3x2 ,
use the formula ab + ac = a(b + c) THREE TIMES, to get:
x3 + ax - 3a - 3x2 = [x3 - 3x2] + [ax - 3a] (group terms)
= x2(x - 3) + a(x - 3) = (x2 + a)(x - 3).
This manipulation is sometimes called "factoring by grouping".
No more factoring is possible.
To return to factoring self-test, hit the "BACK" button (upper left)